鄂尔多斯盆地东胜铀矿田铀源示踪及其地质意义  

Uranium source analysis and its geological significance to Uranium metallogenic evolution in Dongsheng Uranium Ore Field

作　　者：冯晓曦 金若时 司马献章 李建国 赵华雷 陈印 陈路路 汤超 奥琮 王心华 FENG Xiaoxi;JIN Ruoshi;SIMA Xianzhang;LI Jianguo;ZHAO Hualei;CHEN Yin;CHEN Lulu;TANG Chao;AO Cong;WANG Xinhua(Tianjin Center, China Geological Survey, Tianjin 300170)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170

出　　处：《中国地质》2017年第5期993-1005,共13页Geology in China

基　　金：国家重点基础研究发展计划(973)项目(2015CB453006);中国地质调查局项目"煤田勘查区砂岩型铀矿调查与勘查示范"(DD20160127)和联合资助~~

摘　　要：笔者以鄂尔多斯盆地东胜铀矿田的典型矿床——纳岭沟铀矿床为主要研究对象,通过铀矿体及围岩岩石地球化学、电子探针及稳定同位素测试等方法,综合分析了东胜砂岩型铀矿田的铀源及其地质意义。结果表明:主要含矿目标层中侏罗统直罗组在同生沉积过程中,铀预富集达212.45×10^(-6),围岩达41.34×10^(-6);预富集铀主要来自于盆地北缘蚀源区;铀矿体及围岩REE配分曲线总体具一致性,右倾,个别δEu正异常,富集重稀土,两者铀源具一致性;含铀砂岩δ^(13)C_(V-PDB)=-9.7‰,δ^(18)O_(SMOW)=18.9‰,黄铁矿δ^(34)S_(v-CDT)=-27.46‰,经历了强烈的有机地质作用;铀石围绕炭屑、星散状黄铁矿产出,被胶状黄铁矿肢解,铀富集于成岩作用后期。由此认为,直罗组同生沉积过程中预富集的铀为主要成矿铀源,东胜铀矿田属直罗组预富铀重新分配的产物。In order to study the uranium source and its geological significance of the Dongsheng uranium orefield,the geochemistry,electron probe and stable isotopes of ore body and country rock from the Nalingou uranium deposit are selected.The results indicate that the original uranium content of orebody and mudstone is separately212.45×10?6and41.34×10?6,showing strong preenrichment in the process of syngenetic sedimentation.The debris mainly comes from the adjacent Yinshan Precambrian basement,a few from late Paleozoic acid magmatic rocks,and the uranium in the process of pre-enrichment are mainly from the erosion source area of the northern basin.The REE distribution patterns of the uranium ore body and country rock is generally the same,with individualδEu positive anomaly,enrichment of LREE,and the same source of uranium.Theδ13CV?PDB andδ18OSMOW values of the ore bodies are?9.7‰and18.9‰respectively,and theδ34Sv?CDT value of pyrite is?27.46‰,indicating that they experienced a strong organic geological process.Coffinite occur around the charcoal and scattered pyrite,and were cut through by colloidal pyrite.Uranium is enriched after diagenesis.It is believed that the pre-enrichment of uranium in the process of syngenetic sedimentation is the direct and importont source of uranium mineralization,and Dongsheng uranium ore field is the product of diagenesis of Zhiluo Formation.

关 键 词：铀源 直罗组 预富集 成岩成矿 东胜铀矿田 

分 类 号：P619.14[天文地球—矿床学]